Lithium-ion battery cathode active material coated with lithium trimethylsiloxide and method for manufacturing the same

High-Nickel NCM Cathode Materials with HF-Scavenging LiOTMS Pyrolytic Coating

This technology involves surface modification by coating lithium trimethylsiloxide (LiOTMS) onto the surface of high-nickel NCM cathode active materials. It removes HF generated within the battery and suppresses side reactions with the electrolyte.

High-nickel cathode materials, such as NCM811, have faced issues with interfacial instability caused by Ni4+ during charging and accelerated electrolyte decomposition. Furthermore, hydrogen fluoride (HF) generated by reactions with moisture leads to transition metal dissolution and electrode degradation.

This technology involves mixing LiOTMS with the cathode active material in an NMP solvent, applying it to the surface, and heat-treating it at 600–800°C (optimally 700°C). During this process, LiOTMS undergoes pyrolysis to form a stable inorganic surface film. Applicable to ESS cells requiring long lifespans and high-nickel cathode surface treatment processes, it provides a simple way to reduce HF-induced degradation by adding only a coating step to existing slurry processes.

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Key Features:

• Cathode active material for lithium secondary batteries comprising lithium trimethylsiloxide coated on the surface of the cathode active material
• Coating composite with a weight ratio of lithium trimethylsiloxide to cathode active material ranging from 1:1 to 1:100
• Step of mixing lithium trimethylsiloxide and cathode active material in an NMP solvent to coat the active material surface
• Step of heat-treating the coated cathode active material at 600–800°C to form a surface film

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